// 测试程序
public class AccountTest {
    public static void main(String[] args) {
        // 创建储蓄账户对象
        SavingAccount savingAccount = new SavingAccount("张三",123 , 10000.0);

        // 查询并显示账户信息
        savingAccount.printAccountInfo();

        // 计算并显示月利息
        double monthlyInterest = savingAccount.calculateMonthlyInterest();
        System.out.println("月利息: " + monthlyInterest);

        // 更改利率
        SavingAccount.setRate(0.03); // 将年利率更改为3%
        System.out.println("更新后的年利率: " + SavingAccount.getRate() * 100 + "%");
        System.out.println("更新后的月利息: " + savingAccount.calculateMonthlyInterest());
    }
}